our atmosphere there is one law in their formation. Cloud-particles are formed by the condensation of water-vapour o

much to the decay of clouds-in fact, the subject

icularly drawn to this at my manse in Strathmore. In the middle of that exceptionally sultry month, I was arrested by a remarkable transformation scene. It was the hottest May for seventy-two years, and the driest for twenty-five years. The whol

pell there was, in a quarter of an hour, more blue to be seen than clouds. At the same time, near the horizon, a haze was forming, gradually b

d through, the temperature in the cloud-land rose and evaporation took place on the surface of the cloud-particles, until by an untraceable, but still a gradual process throu

This I will illustrate in the n

water-particles are much smaller and far more numerous than in the latter. While the particles in clouds in decay are large enough to be seen with the unaided eye, when the

s called a cirro-stratus cloud-mackerel-like against the blue sky-is carefully observed in fine weather, it will be found that it frequently changes the ripple-marked cirrus in the process of decay to vanishing. Where the cloud is thin enou

aining from clouds and re-formation by evaporation, or the transformation of such clouds as the cirro-stratus into the ripple-marked cirrus, we a